AU2010338095B2

AU2010338095B2 - Photovoltaic module comprising an electrical connection and having an optical function

Info

Publication number: AU2010338095B2
Application number: AU2010338095A
Authority: AU
Inventors: Eric Gerritsen; Philippe Thony
Original assignee: Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2009-12-14
Filing date: 2010-10-28
Publication date: 2013-05-23
Anticipated expiration: 2030-10-28
Also published as: KR20120104237A; ES2534676T3; WO2011080429A3; FR2953998A1; BR112012012688A2; JP2013513936A; ZA201203535B; EP2513977A2; AU2010338095A1; FR2953998B1; EP2513977B1; US20130112241A1; JP5712224B2; WO2011080429A2; CN102782873A

Abstract

The invention relates to a photovoltaic module comprising a plurality of photovoltaic cells (2) electrically connected in series via connection means (3) comprising electrical conductors. Each connection means (3) comprises an optical device having a reflection-diffractive or transmission-diffractive optical behaviour, and each connection means (3) consists of a sheet formed from a material transparent to incident rays containing at least one network of electrical conductor wires (30).

Description

PHOTOVOLTAIC MODULE COMPRISING AN ELECTRICAL CONNECTION AND HAVING AN OPTICAL FUNCTION TECHNICAL FIELD 5 The invention relates to a photovoltaic module that can convert photons from incident light rays to electrical energy. It relates more specifically to the connections between photovoltaic cells of one and the same module. 10 BACKGROUND OF THE INVENTION Generally speaking a photovoltaic module is formed by a plurality of photovoltaic cells 2 each having a front face 20 and a rear face 21. These photovoltaic cells 2 may be monofacial, i.e. having only one active face, or bifacial, i.e. having an active front face and 15 an active rear face, each of the active faces being able to capture and convert photons from incident light rays falling on these active faces to electrical energy. These photovoltaic cells 2 are arranged to have a gap separating them from one another, and are connected to one another electrically in series, via connection means 3 running from the front face 20 of one cell to the rear face 21 of the adjacent cell, as shown in figure 1. 20 The electrical connection between the photovoltaic cells is not optimum because of the deformation sustained by these connection means. Such an arrangement of these connection means requires the provision of a significant gap separating the cells, thereby reducing the active surface of the resulting panel. To this end, a proposal has been made to implement 25 planar connections, which however still screen some of the front face of the cells. Incidentally, a gap separating said cells is still required. In this context, the purpose of this invention is to propose another photovoltaic module that is free from this previously mentioned limitation. The specific purpose of the invention is to 30 propose a photovoltaic module which offers improved electrical efficiency for a given device or module surface. 35 3367308 1 (GHMattera) P90456 AU 2 DISCLOSURE OF THE INVENTION According to a broad aspect, the present invention provides a photovoltaic module comprising a plurality of photovoltaic cells and connection means comprising electrical 5 conductors, wherein the photovoltaic cells are electrically connected in series via the connection means. Each of the connection means comprises an optical device having a reflection-diffractive or transmission-diffractive optical behaviour. Additionally, each of the connection means, being of a planar type (which facilitates manufacturing), consists of a sheet formed from a material that is transparent or semi-transparent to incident rays 10 containing at least one network of electrical conductor wires. In other words, the photovoltaic module uses the electrical connections between the cells as an optical device. The rays redirected by the optical devices may in particular be used to increase the electrical efficiency of the cells. Therefore, whereas the norm is for the 15 connections to take up some of the active surface of the cells, surface which is then lost in terms of efficiency, the invention unusually opts to increase this "lost" surface while conferring thereupon an optical function in order to return photons to the cells thereby compensating for the loss of active surface. 20 Additionally, the optical device may have various optical functions simultaneously, such as transparency and diffraction for example. To advantage, the front face of each cell is connected to the front face of an adjacent cell, and the rear face of said cell is connected to the rear face of another adjacent cell. 25 Preferably, each connection means additionally has an optical behaviour suitable for letting through all or part of the incident light photons. For example, the connection means may be transparent for some wavelengths. 30 According to one embodiment of the invention, the network of conductor wires has a design that can send the diffracted light rays in a direction perpendicular to the direction of flow of the electric current between two interconnected adjacent photovoltaic cells. 4216503_1 (GH4atters) P90456 AU 3 Each cell may have an active front face and an active rear face, and the photovoltaic module may further comprise a rear plate placed opposite the rear faces of the cells, said rear plate having reflecting zones that can send the incident photons towards the rear faces of the cells. 5 For example, the rear plate may additionally have zones that can let through all or part of the light rays. The rear plate may be formed from a transparent material. BRIEF DESCRIPTION OF THE DRAWINGS 10 Other characteristics and advantages of the invention will become clearer from the description given thereof hereinafter, for information purposes and non-restrictively, with reference to the appended drawings, wherein: - figure 1 is a partial diagrammatic view in cross-section of a photovoltaic cell from the prior art; 15 - figure 2 is a partial diagrammatic plane view of a photovoltaic module comprising electrical connection means having a design according to one embodiment of the invention; - figure 3 is a partial diagrammatic plane view of a photovoltaic module comprising electrical connection means having another design according to another embodiment 20 of the invention; - figure 4 is a diagrammatic view of another design of the electrical connection means according to another embodiment of the invention; - figure 5 is a diagrammatic view of another design of the electrical connection means according to another embodiment of the invention; 25 - figure 6 is a partial diagrammatic view in cross-section of a photovoltaic module according to another embodiment of the invention; - figure 7 is a partial diagrammatic plane view of the photovoltaic module in figure 6; - figure 8 is a partial diagrammatic view in cross-section of the photovoltaic module comprising a rear plate provided with reflective means according to one embodiment 30 of the invention; and - figure 9 is a partial diagrammatic view in cross-section of the photovoltaic module comprising a rear plate provided with reflective means according to another embodiment of the invention. 35 3367308_1 (GHMatters) P90456.AU 4 DETAILED DISCLOSURE OF EMBODIMENTS OF THE INVENTION According to the invention, a photovoltaic module 1 comprises a plurality of photovoltaic cells 2 electrically connected in series via connection means 3 each having an optical 5 behaviour. Each connection means 3 consists in this instance of a sheet formed from a material that is transparent or semi-transparent relative to incident rays, and containing conductor wires 30, of nanometric dimension for example. This optical behaviour may be of the reflection-diffractive or transmission-diffractive type. 10 In one embodiment of the invention, and with reference to figure 2, the conductor wires 30 of a connection means 3 are arranged to be spaced apart from one another, parallel to each other and parallel to a direction of flow I of an electric current. Because of the gap separating the conductor wires, the electrical connection means 3 behaves like a diffraction network for 15 the incident light rays. The diffracted rays 4 are sent in a direction perpendicular to the conductor wires or to the direction of flow I of the electric current. In this embodiment, the ratio of the surface occupied by the cells to that of the connection means may be equal to 1. Such a structure may be formed by etching in transparent polymer sheets coated with a thin 20 film of a conductor metal such as aluminium or copper or silver. The conductor wires may also be obtained by printing on polymer sheets using a conductive ink. According to another technical solution, an electrically conductive material is employed, and an optical property is conferred thereupon by structuring the surface thereof. Thus, 25 depending on the form, spacing, and repetition of the designs, the surface of the material becomes a diffraction network. According to another embodiment of the invention and with reference to figure 3, the conductor wires 30 of a connection means 3 are arranged in a so-called fishbone pattern. In 30 other words, the connection means comprises four groups of conductor wires: - a first group 301 of conductor wires arranged parallel to each other, and oriented at an angle of 45* relative to the direction of flow I of the electric current; 3387308_1 (GHMater) P0456.AU 5 - a second group 302 of conductor wires arranged symmetrically to the first group 301 relative to a first axis perpendicular to the direction of flow I of the electric current, said axis being parallel to the faces of the cells; - a third group 303 of conductor wires arranged symmetrically to the second group 302 5 relative to a second axis perpendicular to said first axis, said first and second axes being co-planar; - and lastly a fourth group 304 of conductor wires symmetrical to the first group 301 relative to the second axis. 10 In this embodiment, each of the groups 301, 302, 303, 304 behaves like a diffraction network and the diffracted rays are sent in directions substantially perpendicular to the conductor wires. This pattern confers greater flexibility with regard to the relative arrangement of the cells, as well as to the form thereof. 15 According to another embodiment of the invention and with reference to figure 4, the conductor wires of a connection means may be arranged so as to form grids, which has the same advantage as mentioned above, and which thereby optimises electrical conduction. According to another embodiment of the invention and with reference to figure 5, the 20 conductor wires of a connection means may form elliptical or circular lines. This pattern thereby improves the flexibility of the arrangement. According to another embodiment of the invention and with reference to figures 6 and 7, the cells are bifacial. They are formed in particular from layers of silicon for example, and have 25 a p-doped active face and another n-doped active face. These cells are connected in series via the connection means 3 used in the embodiment in figure 2 and are arranged so that the p type front face of a cell is co-planar with the n-type front face of an adjacent cell. Additionally, the front face of each cell is connected to the front face of an adjacent cell of opposite doping, and the rear face of said cell is connected to the rear face of another 30 adjacent cell, here too, of opposite doping. Furthermore, in order to increase the electrical efficiency of the photovoltaic module, each connection means 3 may additionally have an optical behaviour suitable for letting through all or part of the incident light photons, as shown in figures 8 and 9. Additionally, the 35 photovoltaic module may comprise a rear plate 5 placed opposite the rear faces 21 of the 3387308_1 (GHMatters) P90456.AU 6 cells, said rear plate being provided with reflecting zones 50 that can send back the incident photons falling thereupon towards the rear faces 21 of the cells. As shown in figure 8, it is also possible to provide transparent zones 51 on the rear plate 5 in order to let through the natural light in order to illuminate a room. 5 Another alternative may also comprise providing the rear plate with a reflective device such as a mirror, or a refractive device such as a prism or lens, or else a device such as a concentrator. 10 It is clear from what has been said above that the originality of the invention lies in the fact that the electrical connection means between the photovoltaic cells have an optical behaviour in relation to the incident rays. These connection means may be transparent so as to let through all or part of the light rays which may then be used to increase the electrical efficiency of the photovoltaic cells through the use in particular of reflective means such as 15 mirrors placed on the rear plate of the photovoltaic module in order to send the photons back towards the rear faces of the cells. These means may also be of the diffractive type, i.e. the light rays have a modified trajectory. By increasing the surface between the cells and by making use of the rear face of the bifacial 20 cells, it is possible to increase electrical efficiency while reducing the surface of the cells, and therefore the manufacturing cost. Furthermore, by redirecting some light rays such as infrared rays outwards from the photovoltaic module, it is possible to cool the cells. 25 Modifications within the scope of the invention may be readily effected by those skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove. 30 In the claims that follow and in the preceding description of the invention, except where the context requires otherwise owing to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, that is, to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 35 Further, any reference herein to prior art is not intended to imply that such prior art forms or formed a part of the common general knowledge in Australia or any other country. 42165031 (GHMattes) P90456AUI

Claims

1. A photovoltaic module, comprising: a plurality of photovoltaic cells; and 5 connection means comprising electrical conductors; wherein the photovoltaic cells are electrically connected in series via said connection means , each of the connection means comprises an optical device having a reflection-diffractive or transmission-diffractive optical behaviour, and each of the connection means, being of a planar type, consists of a sheet formed from a material 10 that is transparent or semi-transparent to incident rays containing at least one network of electrical conductor wires.

2. A photovoltaic module as claimed in claim 1, wherein the optical device has a plurality of optical functions simultaneously. 15

3. A photovoltaic module as claimed in claim 1, wherein the optical device has a plurality of optical functions simultaneously, comprising at least transparency and diffraction.

4. A photovoltaic module as claimed in either one of claims I and 2, wherein each of the 20 photovoltaic cells has a front face and a rear face, the front face of each of the photovoltaic cells is connected to the front face of an adjacent one of the photovoltaic cells, and the rear face of each of said the photovoltaic cells is connected to the rear face of another adjacent one of the photovoltaic cells. 25

5. A photovoltaic module as claimed in any one of claims I to 3, wherein each of the connection means has at least one optical behaviour suitable for letting through some or all light photons incident thereon.

6. A photovoltaic module as claimed in any one of claims I to 4, wherein the network of 30 electrical conductor wires has a design that can send diffracted light rays in a direction perpendicular to a direction of flow of an electric current between two of the photovoltaic cells that are interconnected adjacent. 4216503_1 (GHMatters) P90456.AU 8

7. A photovoltaic module as claimed in any one of one of claims I to 4, wherein each of the connection means consists of an electrically conductive material structured so as to produce an optical diffraction network. 5

8. A photovoltaic module as claimed in any one of one of claims I to 6, wherein each of the photovoltaic cells has an active front face and an active rear face, and the photovoltaic module further comprises a rear plate placed opposite the rear faces of the photovoltaic cells, said rear plate having reflecting zones that can send incident photons towards the rear faces of the photovoltaic cells. 10

9. A photovoltaic module as claimed in claim 7, wherein the rear plate additionally has transparent zones that can let through incident light rays.

10. A photovoltaic module substantially as hereinbefore described with reference to 15 figures 2 to 9 of the accompanying drawings. 4216503_1 (GHMalters) P90456 AU